Category: Physics

By Anupum Pant

It takes about 700 litres of dry Nitrogen gas at atmospheric condition to make 1 litre of liquid nitrogen! So, it’s a good idea to take the Nitrogen from air like this person did in his garage. Here, watch how he did it.

By Anupum Pant

Here’s a cool effect you can achieve with just light, olive oil and a few turns of copper wire (or really strong magnets with a larger section of the magnetic field where the magnetic field lines are parallel). This is called the Faraday effect and the physics of it is complicated to be explained on a blog. Not that I know how it exactly works, but it still is cool to just watch a stream of light get influenced by nothing but just a strong magnet!

One interesting application of this effect is faraday rotator, or basically check valve for light – that is to say, a device through which light passes in one direction and not in the other. So, it is transparent if you look at it from one side and opaque from the other side. The video explains this too…

Faraday rotation is an example of non-reciprocal optical propagation. Unlike what happens in an optically active medium such as a sugar solution, reflecting a polarized beam back through the same Faraday medium does not undo the polarization change the beam underwent in its forward pass through the medium. This allows Faraday rotators to be used to construct devices such as optical isolators to prevent undesired back propagation of light from disrupting or damaging an optical system.

By Anupum Pant

It has been said that several hundreds of years ago, during the 600 BC, the Chinese had developed a method to construct a battle armour using just paper. Sounds like an implausible myth. But turns out, after a good amount of testing by mythbusters, it can be said that paper armour probably was real.

By folding paper multiple times, and by layering it with shellac or resin like it used to be done in the old days, or even without any kind of resin in between, paper becomes considerably strong and can stop attacks from arrows, stabs etc, just like an armour is supposed to do. In fact, an armour made of paper is much lighter than its steel counterpart and would have added agility to the warrior’s movements. So, technically it outperforms a steel armour.

 

Image source: PDF

However, when a paper armour gets wet, like we all know, it becomes heavy. It actually becomes heavier than the steel armour. So, it wouldn’t have been a good choice for the Chinese if the battle was being fought on a rainy day, or if a river had to be crossed.

The paper armour made by the mythbusters team was made up of small fragments of folded paper, each of which were about half an inch thick. While just 1mm thick steel did the trick.

The paper did as well as steel in the sword and arrow tests, failing only the blunt-force test, so the team built a full suit of paper armor to match against a period-accurate steel counterpart. – [Mythbusters wikia]

By Anupum Pant

If you go to the Wikipedia’s page for a seemingly banal topic “Frequencies,” at the bottom of the page you’ll find a section that says “Line current.” You may want to read through it, but you won’t have to because I’ll tell you what it says, in short…

This section is particularly interesting because it mentions that when sounds are recorded, a very faint hum that you can’t hear unless you magnify the sound, gets recorded with it. This hum comes from the electricity which powers anything, say a plug socket, which was close to the microphone when the sound was getting recorded.

In the American electricity grids, a 50 Hz AC current produces a different hum in the recording than in 60 Hz European grids. So, sounds recorded in America, and sounds recorded in Europe, or other places which use the 60 Hz frequencies, can be distinguished fairly easily by forensic experts. This gives a great power to forensic experts. And a headache to sound engineers who never want a hum being embedded in their audio.

Now, what the WIkipedia page doesn’t tell you is that this hum carries a greater amount of information than just telling the recordings from continents apart. In fact, there’s apparently enough information to almost know the date on which this recording was done.

There exist laboratories around the world, to assist forensic experts with this task of determining the recording date, which have continuously been recording just the hum of electricity for several years now. They study the tiny fluctuations (in the order of thousandth of a hertz) in these frequency and keep an archive of dates and tags. It has been found that patterns in these hum fluctuations have been varying continuously and in a very systematic fashion over the years.

The recordings sent to the forensic experts can use processing to isolate the hum and match it with the hum of a date from the archives. And then a date on which, or at least a rough date, on which the recording was done.

via [BBC]

By Anupum Pant

This new video by Veritasium has been hiding from almost no one who’s been online in the last few days. I saw it even trending on Facebook. And is clearly enlightening. What impresses me the most is that simple science is being demonstrated in a very interesting way and it is making a mark. Happy about that.

Magnus effect is when a ball or a cyllinder moving in a fluid like air deviates away from it’s predicted path because of the spin. You can see it happening all the time if you carefully see soccer balls, cricket balls and baseballs being thrown with a spin.

Now who’d think there’d be any applications to thsi effect. That is where the genius of Veritasium comes in. There are ships with big rotating cylinders on the top which use the flowing air to make them more energy efficient.

In fact, the flettner aircraft has no wings and it uses the magnus effect to fly around. It was interesting to see the toy fly with a cylindrical wing. Sadly, embedding seems to have been disabled…

[Applications of magnus effect]

By Anupum Pant

There’s yet another state of matter that has gotten added to the list of the other unconventional states which are almost never mentioned in science classes at school. Some of these are plasmas of course, Bose–Einstein condensates, degenerate matter, Supersolids and Superfluids, and Quark-Gluon plasma…

This one is called Jahn-Teller metals. A research team led by Kosmas Prassides of Tokohu University in Japan discovered, or more like invented, this new state of matter which depending on the conditions can be an insulator, metal or superconductor…

The most interesting part about this discovery is that these substances have been seen to show superconductivity at much higher temperatures than what has been seen is substances before. If every thing goes as per plan, this discovery has the potential to offer us new materials which would conduct electricity with zero resistance and wouldn’t require out of the ordinary cooling to do so.

A simple picture about what exactly is this substance can be explained as follows.

It is a crystalline arrangement of these large molecules called the buckyballs – which are basically ball like shells made up of of 60 atoms of carbon arranged uniformly on the surface of a ball. Now, think of these individual balls getting arranged in an orderly fashion, to form a repeating lattice. And then introduce Rubidium in between them to change the distance between them.

Now, when pressure is applied to this system, it undergoes different amount of distortion at different pressures and hence the electronic properties change, depending on how much pressure is applied and how many Rubidium atoms were there in the first place.

more about it on [Vice]

 

By Anupum Pant

I had always thought that the only mechanism which kept bicycles upright is the gyroscopic effect from the spinning wheels. Turns out, there’s a lot more to bikes staying upright than it seems. Basically three separate mechanisms dictate this effect. One of which is the gyroscopic effect.

The other important thing that keeps a bike balanced is the fact that the rod joining the handle and the centre of the front wheel is at a slight angle. This makes the front tire touch at a point slightly behind the point that is vertically lowest… And then there are so many other things, the combination of precise ones even science hasn’t been able to figure out yet.

By Anupum Pant

The navy is using laser to burn stuff and destroy stuff. They have laser guns to fry enemies in almost every sci-fi movie. But did you know that a laser can be used to cool stuff to the temperatures much much lower than anything else can cool them to. Where refrigerators, liquid nitrogen or liquid helium do not work, laser cooling does. And this is how scientists have been able to achieve temperatures to within a millionth of a degree of absolute zero (–273.15°C or –459.67°F). That’s the closest to the lowest temperature we can get to, theoretically.

This is how it is done.

By Anupum Pant

Golf balls are dimpled and tennis balls are fuzzy. That makes them travel fast, by preventing a drag that would created behind smooth balls. The screwdriver floating mysteriously in air, when pointed with a jet of air does that because it’s like a smooth ball being held up by a low pressure zone created behind it, counteracting gravity.

By Anupum Pant

It’s often said that it is physically impossible to fold a piece of paper more than 7 times. It’s a lie. In 2002 a high school girl proved this wrong by folding a 4000 feet toilet paper in half 12 times.

By Anupum Pant

Superlubricity is a phenomenon where friction completely disappears. It happens when when two crystalline surfaces slide over each other in dry incommensurate contact. Now scientists have managed to recreate it artificially by tuning the spacing of individual atoms on a surface. Of course scaling it to macro objects is going to be next to impossible, but like every impossible thing from the past which is totally possible today, we hopefully will see it happen some time in the future.

Researchers made an optical crystal (lattice) of sort, with peaks and troughs of potential and the other surface of ionic crystal to slide over the potential. They found that when the atoms of the ionic crystal were equally spaced, same as the optical lattice the friction was maxed out. But when this spacing did not match, the atoms simply glided over the optical crystal as if there was no friction at all.

By Anupum Pant

Gravity isn’t exactly as simple as Newton described it in his time. That is not to say his work was a farce, but to say that several decades back, the concept of gravity transformed into something very different from what it is still being taught in schools. What Newton said was of course true to some extent because his laws were valid only if you were measuring things from an inertial frame of reference.

By Anupum Pant

Under the building 82 of Eastman park (Kodak park) in Rochester, New York, for about 30 long years, there existed a secret nuclear reactor which contained 3.5 pounds of weapons grade Uranium (highly enriched uranium) to produce neutrons for research. Of course, when it was under a building that belonged to Kodak, the reactor belonged to Kodak as well – to an American technology company focused on imaging solutions and services for businesses.

It may come as a surprise as to why would an imaging company have something like that in their basement. But this device, called the Californium Neutron Flux Multiplier (or CFX) was something Kodak had a perfect justification to own. The device was used to check materials and chemicals for impurities.

The 14 by 24 foot cavity in the ground where it was kept was very nicely shielded with several feet of concrete and earth on all sides, so safety was never a problem. In its full 30 year period for when it was there, there wasn’t a single safety issue.

The reactor was quite a well guarded secret because it used weapons grade uranium, although in not a quantity enough to make a big bomb. However, it operation was done with permission from the federal regulators.

In the year 2007 the highly enriched uranium was safely removed, with armed guards and was taken to a nuclear facility in South Carolina.

More at [Democrat and Chronicle]